Fan



Sept. 20, 1938.

M. A. SMITH, JR

FAN

. R 2 G mm m l mM H fl ,JWA

A Z 2 A m 43 M x a 4 v 0 l v w m Sept. 20, 1938. M. A. SMITH, JR

FAN

Filed Feb. 9, 1935 3 Sheets-Sheet 2 INVENTOR.

I n 6%. A A

my y Sept. 20, 1938.

M. A. SMITH, JR

Filed Feb. 9, 19:55

3 Sheets-Sheet 3 INVENTOR. Mean flu 6'. 6/4071, d2. BY g f m ATTORNEY II. I l mH hH" HI wmmwmmnwm.

9Q; Z W a 1; 4T 7. Z 8 I4 0 Patented se ezo, 193s UNlTE'D' STATES" PATENT OFFl-CE saith, Jnfsz th m, Ind., some ifleffaimo'r'io fifit tm south Bend Application February 9, 1}, Serial No. 5,691 2 Claims. (cl. sat-m) This invention relates to fans, and more particularly to ventilating fans.v

- The object of the invention is to increasethe v emciency, and to decrease the manufacturing cost of ventilating fans by the use of certain novel constructional features hereinafter more fully described.

' Accordingto a preferred embodiment of the invention, a Venturi-shaped air intake ring formed in a unique manner is employed to'produce smooth airflow past a novel fan designed to produce uniform airflow over its entire working area.

Other important features of the invention reside in the novel means employed to fix the driving motor to the air intake ring, and to the connection between the fan and the driving shaft of the motor.

Other'important features of the invention will" 30 Figure 2 is a side'elevation, partly in section.

ofthefanshowninl igure 1;

'Figure 3 is a side elevation partly in section, of

" the hub employed to fix, the fan to the driving motor;

I 5 Figure} isa front elevation similar toFig m-e 1 but showing a different embodiment of the invention; I Figure 51s a side elevation of the fan shown in 1 Figure. 3; Figure 6 isa rear elevation, similar to Figure 3,

but showing a different embodiment of ,the invention: s

t Figure 'l is a side elevation of. the fan shown in Figure 6; and

'HofFigure'l.

Referring to the drawings, andmore particularly to Figure 1, there is shown a ventilating fan having a driving motor [I and a driving shaft I2.

50 A hub is having two sections of reduced outer v diameter l6 and i8 is flxed to the driving shaft l2 by any suitable means such as the screws 20. A flange 22 is received over the section, II of the hub-l4. and is fixed. thereto by shear-riveting a 166 portion ofthe section it into a countersunk secwherein similar reference- Flgure 8,is an enlarged view, taken on the line tion II of the flange 22. A bladed fan 28 is received over the projection ll of the hub i4, and is fixedto the flange 22 by any suitable means such as the rivets 2L 7 The blades of the fan are designed-to de- 5 liver air uniformly across their working length. The peripheral velocity of the portions of the blade closer to the hub is less than the peripheral velocity of points more distantly removed from the hub. It is therefore necessary to progressively increase either the angle of incidence or the effective width of the blade as the hub is approached in order to deliver a uniform quantityof air: It has been found that better results can be accomplished by progressively increasing both [the effective width, and-the angle of incidence of the blade as the peripheral velocity of the blade decreases as the hub is approached. In view of the fact that the peripheral velocity of the portions of the blade adjacent to the hub, commonly called the root of the blade, is very low, it has been found impractical to attempt to employ this section of the blade to drive air. The portion of the blade having the highest angle of incidence is the portion of the working length closest to the hub. The root of the blade must be sufllciently strong to withstand considerable bending in order that'the section of the working length of the blade closest to the hub can be carried at the necessary high angle of incidence. The root section of the blade is therefore made of uniform cross section in order to produce uniform torsional strength so.that the blade maybe easily bent or formed to the high angles necessary at the beginning of the working section, without danger of overstressing the ma- The fan 28 is surrounded by a Venturi-shaped air intake ring 30 designed to produce smooth air flow and to prevent eddies in the air before it is acted upon by the propeller 28.

The ring it is formed in a novel manner by butt-welding a strip of material to form a hollow cylinder of proper diameter to form the desired ring, The cylinder is then passed between a pair 5 of rolls which deform it to give it the proper Venturi shape. The cylinder is then removed from-the forming rolls and placed in a squeezer. The squeezer is so designed as to place equal pressure on all points about the periphery of the cylinder. The squeezing operation is continued until the material of the cylinder is stressed beyond in elastic limit, and when so stressed it will retain its shape permanently.

Two Venturi-shaped rings may be formed together channel-shaped and then split to separate them after the squeezing operation, or one may be formed at a time, as desired. The rings may be formed of any desired material such as aluminum or steel.

Means are provided to fix the driving motor Hi to the ring 30. Motor support struts 32 formed of seamless tubing or rectangular strip metalof very thin cross section, (having the dimension parallel to air fiow many times greater than the dimension perpendicular to air flow) are spot- -weided to a retaining ring 33, fixed tothe driving motor ill by the screws 35, and extend to the ring 30. The motor support struts 32 are preferably spot-welded to a T-shaped member 34 fixed to the ring 30 in any suitable manner, as by rivets 36. The support struts 32 are so proportioned that the dimension parallel to air flow is many times greater than the dimension perpendicular to air flow.

In the smaller type fans illustrated in Figures 1 and 2, four motor support struts arranged as shown in Figure 1 may be sufficient to support the driving motor l and the fan 26. In the larger types of fans it has been found desirable to employ six motor support struts 32 arranged as shown in Figure 4.

To support the largest types of fans it has been found advisable to use a triangulated structure as shown in Figure 6. In this structure the motor support struts 32 welded to the T-shaped members. 34 form a triangular-shaped framework across the ring 30. Reinforcing members 38 strengthen the framework and form a support to which the feet 40 of the motor in maybe fastened by any suitable means, such'as the bolts 42. If desired' resilient washers 44 formed of rubber or other sultable'material may be interposed between the feet'40 of the motor and the motor support, to damp out vibration.

In the devices shown in Figures 1-5 the thrust and torque of the fan 23 are transmitted through the motor retaining ring 33 to the motor support struts 32. i

In the device shown in Figures 6 and 7 the thrust and torque of the fan 26 are transmitted through the feet 40 bolted to the reinforcing Although the invention has been described with particular reference to certain specific embodiments, it is not intended to limit the scope of the invention to the embodiments shown, nor otherwise than by the terms of the following claims.

I .1. A ventilating fan comprising a driving motor including a shaft and a housing, a bladed fan having a working area designed to deliver air at uniform velocity, a generally conical shaped air flow directing ring and an an outlet passage of substantially the same diameter as the fan, and means including a plurality of thin relatively wide brace members fixed to the flanged section of the air fiow directing ring and extending across said ring to form a generally triangular shaped framework to receive the housing of the driving motor to hold the ends of the. blades of the fan adjacent and rearwardly of the section of the ring of substantially the same diameter as the fan.

2. In a ventilating fan, a driving motor includ ing a housing and a driving shaft, a hub fixed to the driving shaft, a flange riveted to the hub, a bladed fan fixed to the flange, said blades having working sections designed to deliver air at uniform velocity over the working area of said blades and a root section of uniform cross section to resist the concentration of bending stresses de-- veloped in the fan, a Venturi-shaped ring surrounding the. fan, and means including thin relatively long supports extending across the Venturi-shaped ring fixed to the housing of the driving motor to hold the outer ends of the fan blades adjacent the restricted section of the Venturishaped ring.

' MARSHALL a 5mm, JR. 

